Background Out-of-hospital cardiac arrest (OHCA) is a leading cause of sudden cardiac death worldwide. Researchers have found significant pathophysiological differences between females and males and clinically significant sex differences related to medical services. However, conflicting results exist and there is no uniform agreement regarding sex differences in survival and prognosis after OHCA. Therefore, we investigated the relationship between the prognosis of OHCA and sex factors. Methods We comprehensively searched the PubMed, Embase, and Cochrane databases and obtained a total of 1042 articles, from which 33 studies were selected for inclusion. The pooled odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using a random-effects model. Results The meta-analysis included 1,268,664 patients. Compared with males, females were older (69.7 years vs. 65.4 years, p < 0.05) and more frequently suffered OHCA without witnesses (58.39% vs 62.70%, p < 0.05). Females were less likely to receive in-hospital interventions than males. There was no significant difference between females and males in the survival from OHCA to hospital admission (OR 0.99, 95% CI 0.89–1.1). However, females had lower chances for survival from hospital admission to discharge (OR 0.59, 95% CI 0.48–0.73), overall survival to hospital discharge (OR 0.73, 95% CI 0.62–0.86), and favorable neurological outcomes (OR 0.62, 95% CI 0.47–0.83) compared with males. Conclusions Our results indicate that the overall discharge survival rate of females is lower than that of males, and females face a poor prognosis of the nervous system. This is likely related to the pathophysiological characteristics of females, more conservative treatment measures compared with males, and different post-resuscitation care. However, these findings should be interpreted with caution due to the presence of several confounding factors.

Circular RNAs (circRNAs) are a group of covalently closed, endogenous, non‐coding RNAs, which exist widely in human tissues including the heart. Increasing evidence has shown that cardiac circRNAs play crucial regulatory roles in cardiovascular diseases (CVDs). In this review, we aimed to provide a systemic understanding of circRNAs with a special emphasis on the cardiovascular system. We have summarized the current research on the classification, biogenesis and properties of circRNAs as well as their participation in the pathogenesis of CVDs. CircRNAs are conserved, stable and have specific spatiotemporal expression; thus, they have been accepted as a potential diagnostic marker or an incremental prognostic biomarker for CVDs.

The proprotein convertase subtilisin/kexin type 9 (PCSK9) acts via a canonical pathway to regulate circulating lowdensity lipoprotein-cholesterol (LDL-C) via degradation of the LDL receptor (LDLR) on the liver cell surface. Published research has shown that PCSK9 is involved in atherosclerosis via a variety of non-classical mechanisms that involve lysosomal, inflammatory, apoptotic, mitochondrial, and immune pathways. In this review paper, we summarized these additional mechanisms and described how anti-PCSK9 therapy exerts effects through these mechanisms. These additional pathways further illustrate the regulatory role of PCSK9 in atherosclerosis and offer an in-depth interpretation of how the PCSK9 inhibitor exerts effects on the treatment of atherosclerosis.